1. Field of the Invention
The present invention relates to a system and method of pointed position detection that use a differential image, a presentation system and a program.
2. Description of Related Art
It is already known in the art to use a CCD camera to acquire an image display region in which a pointing action is implemented, during a presentation, and detect the pointed position.
There are serious problems concerning how the position is to be detected in such a case.
In one method that has been proposed for detecting such a position, differential images of a plurality of frames are extracted in sequence, and the tip of the pointed position is detected.
Since it is not possible with this method to extract a differential image accurately when the pointing action is halted, however, it can be difficult to detect the pointed position.
The present invention was devised in the light of the above described technical problem and has as an objective thereof the provision of a pointed position detection system and method, a system, a projector and a program that make it possible to create a suitable differential image, even when the pointing action is in a halted state, when using such a differential image.
(1) According to a first aspect of the present invention, there is provided a pointed position detection system which detects a position pointed by a pointer within a predetermined image display region, the system comprising:
image pick-up means for picking up an image of the image display region;
means for storing an image for differential image generation which is generated by picking up an image of the image display region on which a uniform image is displayed;
differential image extraction means for extracting a differential image based on the image for differential image generation and a pointing image which is generated by picking up an image of the image display region in which a pointing action is performed; and
means for detecting a pointed position in the pointing image comprised within the image display region, based on the extracted differential image.
(2) According to a second aspect of the present invention, there is provided a pointed position detection system which detects a position pointed by a pointer within a predetermined image display region, the system comprising:
image pick-up section for picking up an image of the image display region;
section for storing an image for differential image generation which is generated by picking up an image of the image display region on which a uniform image is displayed;
differential image extraction section for extracting a differential image based on the image for differential image generation and a pointing image which is generated by picking up an image of the image display region in which a pointing action is performed; and
section for detecting a pointed position in the pointing image comprised within the image display region, based on the extracted differential image.
(3) According to a third aspect of the present invention, there is provided a computer-usable program embodied on an information storage medium or in a carrier wave for implementing a presentation system that detects a pointed position in a predetermined image display region, the program implementing in a computer:
means for storing an image for differential image generation which is generated by picking up an image of the image display region on which is displayed a uniform image by means of image pick-up means;
differential image extraction means for extracting a differential image based on the image for differential image generation and a pointing image which is generated by picking up an image of the image display region in which a pointing action is performed; and
means for detecting a pointed position in the pointing image comprised within the image display region, based on the extracted differential image.
(4) According to a fourth aspect of the present invention, there is provided a pointed position detection method of detecting a position pointed in a predetermined image display region, the method comprising the steps of:
storing an image for differential image generation which is generated by picking up an image of the image display region on which is displayed a uniform image;
extracting a differential image based on the image for differential image generation and a pointing image which is generated by picking up an image of the image display region in which a pointing action is performed; and
detecting a pointed position in the pointing image comprised within the image display region, based on the extracted differential image.
This aspect of the invention makes it possible to create a suitable differential image in which is reflected the pointed position when the pointing action is in a halted state, by obtaining a difference between a uniform image and an image in which the pointing action is performed, thus making it possible to accurately detect the pointed position.
(5) The image for differential image generation and the pointing image may be generated by picking up an image formed by invisible rays.
This makes it possible to perform image processing based on a suitable image that is not greatly affected by the light projected into the image display region during the processing of the image, by applying an image that was formed by invisible rays, thus increasing the accuracy with which the pointed position is detected.
(6) The invisible rays may be infrared rays; and the image pick-up means may pick up an image formed by infrared rays, through an infrared transmission section that allows only infrared rays to pass.
This eliminates unwanted light components by taking an image formed by infrared rays through the infrared-transmission section. As a result, accurate position detection is achieved by a reduction in the noise generated by changes in the unwanted light components.
Note that the infrared rays in this case are generally electromagnetic waves of wavelengths of 700 nm to 1 mm.
(7) The pointed position detection system may further comprise an auxiliary light source which projects infrared rays toward the image display region when picking up an image formed by infrared rays.
This provision of an auxiliary light source ensures that infrared rays can be provided for the pickup of the image, even when the system is used in a location without sunlight.
(8) The pointed position detection system may further comprise:
image display means for displaying an image in the image display region; and
control means for determining whether or not update of the image for differential image generation is necessary, based on the differential image which has been extracted based on the image for differential image generation and a non-pointing image generated by picking up an image of the image display region in which no pointing action is performed, and controlling the image display means to display the uniform image for a predetermined short period of time and also controlling the image pick-up means to pick up an image of the image display region in which the uniform image is displayed and thus capture a new image for differential image generation, when the update is necessary.
(9) The program may further implement in a computer, control means for determining whether or not update of the image for differential image generation is necessary, based on the differential image which has been extracted based on the image for differential image generation and a non-pointing image generated by picking up an image of the image display region in which no pointing action is performed, and controlling image display means which displays an image in the image display region to display the uniform image for a predetermined short period of time and also controlling the image pick-up means to pick up an image of the image display region in which the uniform image is displayed and thus capture a new image for differential image generation, when the update is necessary.
(10) In the pointed position detection method, the step of extracting a differential image may include:
a step of extracting a differential image based on the image for differential image generation and a non-pointing image generated by picking up an image of the image display region in which no pointing action is performed;
a step of determining whether or not update of the image for differential image generation is necessary based on the extracted differential image;
a step of displaying the uniform image for a predetermined short period of time when the update is necessary; and
a step of picking up an image of the image display region in which the uniform image is displayed to capture a new image for differential image generation.
This makes it possible to re-capture an image for differential image generation whenever necessary, to replace it with the previously stored image for differential image generation. Even when noise such as extraneous light such as daylight increases, such noise components can be eliminated by the image for differential image generation, thus enabling accurate detection of the pointed position in answer to changes in the environment.
Note that since the uniform image is displayed for only an instant, it is possible to re-create the image for differential image generation without imparting any sort of unpleasant visual feeling to people viewing that image.
(11) The pointed position detection system may further comprise:
image display means for displaying an image within the image display region; and
control means for controlling the image display means to display the uniform image for a predetermined short period of time at a predetermined temporal spacing, and also controlling the image pick-up means to pick up an image of the image display region in which the uniform image is displayed and thus capture a new image for differential image generation.
(12) The program may further implement in a computer, control means for controlling image display means which displays an image in the image display region to display the uniform image for a predetermined short period of time at a predetermined temporal spacing, and also controlling the image pick-up means to pick up an image of the image display region in which the uniform image is displayed and thus capture a new image for differential image generation.
(13) The pointed position detection method may further comprise:
a step of displaying the uniform image for a predetermined short period of time at a predetermined temporal spacing; and
a step of picking up an image of the image display region in which the uniform image is displayed to capture a new image for differential image generation.
This ensures that a differential image is always created to suit the current environment, thus enabling accurate position detection, by re-creating the image for differential image generation at regular intervals and replacing it with the previous image for differential image generation.
Note that since the uniform image is displayed for only an instant, it is possible to re-create the image for differential image generation without imparting any sort of unpleasant feeling to people viewing that image.
(14) The control means may control the image display means to display a predetermined image for calibration during a calibration step, to obtain correspondence between the image display region and an image processing region.
This ensures accurate pointed position detection by obtaining correspondence between the image display region and the image processing region, based on the result of pickup of an image for calibration purposes, by way of example.
Note that the image for calibration in this case is preferably an image in which is disposed a plurality of points at positions that are a predetermined distance from a central position of the image.
(15) According to a fifth aspect of the present invention, there is provided a presentation system which comprises processing means that performs predetermined data processing which reflects a pointed position detected by the above-described pointed position detection system.
The program may further implement in a computer, processing means that performs predetermined data processing which reflects a pointed position detected by the above-described means.
This makes it possible to perform various types of processing based on position detection.
In this case, this data processing could be calculations of the display position of a cursor, changes in the display of the cursor, icon pointing determination, or icon display modification, by way of example.
(16) The processing means may perform positional control of a cursor comprised within a display image, based on the detected pointed position.
This enables control of the position at which a cursor is displayed, according to the pointed position. Since this makes it possible for a cursor to follow the pointed position accurately during a presentation or the like, with no false recognition caused by extraneous light, it is possible to produce effective presentations.